Caching Search Results

The Watson™ Explorer Engine indexer stores a cache of the results of previous searches on disk. This cache is a set of small binary files that record the top results for a query, which makes it possible to page through search results without recomputing the entire result set. The Watson Explorer Engine results cache is stored in the cache subdirectory of the directory where your search collection is stored.

Watson Explorer Engine enables you to configure the following basic aspects of the search result cache:

  • whether search results are cached
  • the amount of disk space to use for the cache
  • the number of queries after which results are purged from the cache

The size of the result cache is configured on a per-collection basis in the Advanced section of a search collection's Configuration > Searching tab. Click edit on the Configuration > Searching tab, scroll down to the Advanced section, and click the arrow to the left of the Advanced label to expand that section. The value of the Result cache option specifies the size of the result cache that you want to use for this collection. The default size of the result cache for any search collection is 100 MB. You can set the value of the Result cache option to 0 in order to disable result caching.

The frequency with which the result cache for a collection is cleaned is configured on the same tab by setting a value for the Result cache cleaning period option. This option specifies the approximate number of queries after which the result cache will be cleaned. By default, the result cache is purged after every 100 queries.